I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Because employment is at-will, an employer unfortunately does not need to give a reason for terminating employment. There are no state or federal laws that require an employer to give an employee a trial before letting them go, and no laws that require paying a severance package. An employee can be let go at any time, for any reason that isn't based on illegal discrimination (meaning your race, ethnicity, religion, sexual orientation, age over 40, or gender/gender identity). And I'm sorry to say, that also means there is no recourse when a person is fired without understanding why. There isn't even a legal right to be given a reason.
They ARE required to offer you COBRA continuation health insurance, if your employer had 20 or more employees. If you didn't receive any information, call your state's insurance commission.
They are also not permitted to STOP you from getting a job elsewhere. They can honestly tell other employers why you were let go if asked. They cannot lie or make up a reason, and they should not be reaching out to potential employers to stop you from getting a job if they're not asked. That could give rise to a suit for intentional interference with employment. If you have evidence that they're doing that, you may be able to have a local attorney send them a "cease and desist" letter, or file a lawsuit for damages.
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